Pettigen allegedly argued with his mother, who he claims pulled a gun on him, before he grabbed a hammer off the bedroom wall to knock the weapon from her hand.

He then allegedly returned with a tomahawk and beat her before shooting her in the back four times with a gun he retrieved from a wardrobe.

The son is then believed to have sliced open her chest with a knife and removed her heart with his bare hands before putting it back in her body.

Pettigen reportedly told police he murdered his mum because she was killing herself with the prescription painkillers oxycodone, which he claims she had become addicted to after hip and knee problems and surgery.

He allegedly added that, after the sickening attack, he masturbated because "he needed to be with himself and needed a release after the event" before going out drinking with friends, charging documents seen by the Daily News show.